Perceptual dimorphism: Dark squares appear to be in front or light ones appear to be in front.pic.twitter.com/KXmlFANt7U
12:32 AM - 18 Feb 2018
0 replies
6 retweets
24 likes
Loading seems to be taking a while.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.